Models

The integrated cardiovascular model combines a simple model of the cardiovascular system (Smith, 2004) and a model describing baroreflex control of the heart (Bugenhagen, 2010). The resulting closed loop model simulates pressures flows and volumes in the rat cardiovascular system as well as the dynamics of the baroreflex system. Both the Smith and Bugenhagen models are available for download in the links below. A Matlab version of the integrated model is included for comparison.

Figure 1: The integrated model combines the simple cardiovascular model of Smith et al. [1] and the baroreflex model of Bugenhagen et al. [2]. The two ventricles of the heart are labeled ‘lv’ and ‘rv’, for left and right ventricle. The systemic circulation is represented by two compliant compartments, labeled ‘ao’ and ‘vc’ for aorta and vena cava. Similarly, the pulmonary circulation is represented by two compartments labeled ‘pa’ and ‘pv’ for pulmonary artery and pulmonary vein.

Figure 2: Simulation of integrated cardiovascular mechanics model. The upper panel shows simulated left-ventricular and aortic pressure during baseline conditions, during a transient 20 mmHg increase in thoracic pressure (period labeled ‘Valsalva’, and during recovery. The lower panel shows predicted heart rate during the simulation.

Model Notes:

mmHg increase in thoracic pressure (period labeled ‘Valsalva’, and during recovery. The lower panel shows predicted heart rate during the simulation.

An additional heart rate parameter was added to the integrated model to convert HR to seconds per beat as required for the driver function in Smith et al.
In Smith et al. the heart driver is an equation with constant output. The inclusion of the Baroreflex necessitates modifying the driver to be a function of heart rate.
The ventricular elastance parameters in Smith et al. were recast as functions of heart rate.
A description of the integration workflow can be found here.